Exploration of the Active Domain of Polysaccharide LBP1C-2 Targeting β-Subunit-2 of Voltage-Gated Potassium Channel
Objective This study aims to elucidate the structure-activity domain of LBP1C-2 targeting Kvβ.2 through an exploration of the structure-activity relationship.This study may also provide the scientific basis for the development of drug candidate with anti-early-onset dementia activity.Methods After partial acid hydrolysis,various structural fragments were obtained and subjected to monosaccharide composition and molecular weight analysis.Potential target proteins were selected using a protein chip,followed by validation of the targeting specificity of each structural fragment using surface plasmon resonance(SPR)technology.Results Through high-throughput screening using the HuProtTM human protein array,potential target protein Kvβ.2 was identified for LBP1C-2.SPR experiments revealed a strong binding affinity between LBP1C-2 and Kvβ.2 protein,with a binding constant(KD)of 1.9×10-7 M.The various structural fragments of LBP1C-2 exhibited different binding strengths with the target protein Kvβ.2.Among them,the segment LBP1C-2-1I(18.1 k Da)with a molar ratio of rhamose to galecturonic acid of 1:1 showed a binding strength to Kvβ.2 similar to that of the polysaccharide LBP1C-2,with a KD of approximately 3.3×10-7 M.Structural analysis indicates that the structure of LBP1C-2-1I contains 1,2-linked Rha and 1,4-linked GalA which are alternatively linked.The acid-hydrolyzed extracellular portion corresponding to this segment,LBP1C-2-1O may also bind to Kvβ.2.However,compared to other segments,it demonstrated a higher tendency to dissociate from the protein.Knockdown of the KCNAB2 gene(Kvβ.2)in BV2 cells inhibited the uptake of Aβ in BV2 cells,suggesting that protein Kvβ.2 may be a functional protein in the development of Alzheimer's disease.Conclusion LBP1C-2-1I has been identified as the primary active domain through which LBP1C-2 targets Kvβ.2.This suggests that the active domain of LBP1C-2 predominantly resides on the main chain rather than the side chain.This study provides crucial insights for a deeper understanding of the anti-early-onset dementia activity of LBP1C-2 and lays an experimental foundation for the design and development of targeted drugs for anti-early-onset dementia based on Lycium barbarum polysaccharides.
PolysaccharidesLycium barbarumKvβ.2 proteinActive domainsTargeted research
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